Zinc

How much zinc do I need?

The amount of zinc you need each day depends on your age. The following table from the National Institute of Health USA, shows the average recommended amounts for different age groups.

What foods provide zinc?

Zinc is found in a wide range of foods such as:

• oysters (best source of zinc)
• red meat, poultry and seafood such as crab and lobsters (good sources)
• fortified breakfast cereals (good source)
• beans, nuts, whole grains (some zinc)
• dairy products (some zinc).

By eating a wide range of food groups, it is rare to develop zinc deficiency.

Who is at higher risk of zinc deficiency?

• People who have had gastrointestinal surgery, such as weight loss surgery, or who have digestive disorders, such as ulcerative colitis or Crohn's disease.
  • These conditions decrease the amount of zinc that the body absorbs and increase the amount lost in the urine.
• Vegetarians
  • Meat is a good source of zinc which vegetarians miss out of.
  • Beans and grains often eaten by vegetarians have a compound that reduces the absorption of zinc.
• Older infants who are breastfed
  • Breast milk does not have enough zinc for infants over 6 months of age.
  • They should be given foods that have zinc, such as pureed meats.
  • Formula-fed infants get enough zinc from infant formula.
• People who drink a lot of alcohol.
• People with sickle cell disease may also need more zinc.

Zinc supplements

If you are one of the higher risk groups mentioned above, talk with your doctor or nurse to see if you need to take a zinc supplement or multivitamin (which usually have zinc in them).

There are some other cases where zinc supplements can help:

The common cold

• Some studies suggest that zinc may help speed recovery from the common cold and reduce its symptoms if taken within 24 hours of cold symptoms.
• However, more research is needed before this can be recommended as a treatment for the common cold.

Age-related macular degeneration (AMD)

• AMD is an eye disease that gradually causes vision loss.
• Research suggests that zinc might slow down the progression of early AMD worsening into advanced AMD.
• More research is needed before this is routinely recommended.
• Talk with your doctor whether this is right for you or not.

Children with diarrhoea in low-income countries

• Children in low-income countries often die from diarrhoea.
• Research studies have shown that zinc deficiency is common in these countries and dietary supplements help reduce the symptoms and duration of diarrhoea in these children.
• The World Health Organization and UNICEF both recommend that children with diarrhoea take zinc for 10–14 days (20mg/day, or 10mg/day for infants under 6 months).

Can zinc be harmful?

Yes, like most nutrients, too much zinc can be harmful. Signs can include nausea, vomiting, loss of appetite, stomach cramps, diarrhoea, and headaches.

Zinc can be present in some denture adhesive creams:

• Using large amounts of these products, well beyond recommended levels, could lead to excessive zinc intake and copper deficiency.
• This can cause neurological problems, including numbness and weakness in the arms and legs.

Interactions with other medicines

If you are taking zinc supplements, it can interact or interfere with medicines you have been prescribed by your doctor.

• Quinolone or tetracycline antibiotics reduce the amount of both zinc and the antibiotic that the body absorbs.
• Zinc dietary supplements can reduce the amount of penicillamine (a drug used to treat rheumatoid arthritis) that the body absorbs.
• Thiazide diuretics increase the amount of zinc lost in the urine.

Learn more

Consumer zinc factsheet National Institutes of Health, 2011
Drugs and supplements – zinc safety Mayo Clinic, Mayo Foundation for Medical Education and Research, 2013
Zinc – background information Mayo Clinic, Mayo Foundation for Medical Education and Research, 2013

References

1. Singh  M, Das  RR. Zinc for the common cold Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD001364. DOI: 10.1002/14651858.CD001364.pub4.